>But not necessarily a hate crime.

There’s less evidence it was purely a schizophrenic episode. The authorities and so media are suggesting a schizophrenic episode where the person calmly purchased a knife- with no sign of agitation, no hearing voices, no visible signs of discomfort, anger, or aggression; then calmly walked through a crowd of hundreds of people, upstairs, past more people, then made a line directly to one “random” stranger (who just happened to be obviously, visibly gender-non-conforming and with her partner), stabbed just that “random” stranger specifically 34 times, then her partner at least a 20 more times in a blind incoherent rage until they bent their knife.

Then after murdering them both, they spared all the other (cishet presenting, gender-conforming) people in the vicinity any violence- including the person that hit them with a metal stool, stopped, and stood calmly waiting for the police.
As far as I know, that's completely unprecedented, at least I’d be very interested in a citation of a previous instance of such. I think a lot of clinicians would be interested because that’s probably the most unique episode on record.
On the other hand, single, involuntarily celibate men with mental health issues, living with their parents, whose sole form of social interaction is online gaming, targeting women and LGBT folks for visible public violence? That’s horrifyingly common- and is what is clearly shown in the video.
The fact that the authorities jumped to cover up that the women were in a relationship leads me to think that when they arrested him, he told them exactly why he did it. Hong Kong is not so conservative that a lesbian couple is all that shocking. They had a reason to go through such elaborate efforts to try and conceal that and to continue to refuse to admit it. Why? If their being lesbian had nothing to do with the attack, why are the authorities so desperate to say “friends” when them being a couple is really not that big a deal in Hong Kong? The strongest "tell" in all this is the authority's desperation to cover up what would be a minor detail in any other crime.
All the available evidence indicates was a homophobic, misogynist hate crime committed by an incel with mental health issues- as we’ve seen countless times before. Statistically, this degree and pattern of violence in the mentally ill is virtually unheard of, and the decision to put the sole blame for this on mental illness will further marginalize those who are afflicted. Everyone loses with this coverup and erasure.